Writing instrument



FIG. 1 is a side elevational view of a writing instrument showing my new design;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a top plan view thereof;

FIG. 4 is a bottom plan view thereof;

FIG. 5 is an exploded side elevational view with the cap removed; and

FIG. 6 is a side elevational view with the cap on the end opposite the writing point. 

The ornamental design for a writing instrument, substantially as shown and described. 